Many building codes are now requiring or will soon require hurricane shutters on all new homes built in coastal areas. Similar requirements for buildings other than homes are anticipated as well. The South Florida Building Code, 1994 Edition, requires that storm shutters shall be designed and constructed to insure a minimum of a one inch separation at maximum deflection with components and frames of components they are to protect unless the components and frame are designed to receive the load of storm shutters.
The determination of actual wind loading on building surfaces is complex and varies with wind direction, time, height above ground, building shape, terrain, surrounding structures, and other factors. The American Society For Testing And Materials (ASTM) has promulgated a Standard Test Method For Structural Performance of Exterior Windows, Curtain Walls, And Doors By Uniform Static Air Pressure Difference and its designation is E330-97 and was published April 1998. The test method requires that the person specifying the test translate anticipated wind velocities and durations into uniform static air pressure differences and durations. Durations are considered because most materials have strength or deflection characteristics which are time dependent. Testing under this method is performed in a test chamber which measures the pressure difference across the test specimen.
Similarly, ASTM has declared a Standard Test Method For Water Penetration Of Exterior Windows, Curtain Walls, And Doors By Uniform Static Air Pressure Difference which includes a water spraying apparatus within the test chamber. See, ASTM designation E331-96. Leakage rate testing can be done under the ASTM Standard Test Method For Determining The Rate Of Air Leakage Through Exterior Windows, Curtain Walls And Doors Under Specified Pressure Differences Across The Specimen. See, ASTM designation E283-91.
When a building envelope is breached devastating pressure differentials cause large amounts of damage. Kinetic energy due to the velocity of the fluid is proportional to the square of the velocity. Energy from the wind, therefore, pressurizes the interior of a home or other structure which in combination with the profile of the roof makes the roof, in effect, act like an airplane wing causing it to blow off the remaining structure. Windload and impact resistance requirements depend on the particular community promulgating the requirements.
The American Society of Civil Engineers"" Standard 7 is being increasingly used by public regulators in formulating requirements. In some areas of high probability for high wind occurrences, such as hurricanes, existing homes are required to upgrade windows and doors or add shutters and other protective devices to building openings to protect them.
Conventional storm window protection as shown in U.S. Pat. No. 4,065,900 to Eggert, U.S. Pat. No. 4,069,641 to De Zutter and U.S. Pat. No. 4,478,268 to Palmer are methods of attaching outer coverings to window or door openings. U.S. Pat. No. 4,065,900 to Eggert discloses an apparatus for framing and fastening a secondary glazing pane which utilizes a hinge. U.S. Pat. No. 4,069,641 to De Zutter discloses a storm window frame which utilizes double-faced tape to mount the storm window frame and, hence, the storm window. U.S. Pat. No. 4,478,268 to Palmer discloses a hard flexible curtain door, a tensioned storage or wind-up drum, and channels in which the door resides. The door moves out of the channels under impact and is wound up to open for vehicle passage.
U.S. Pat. No. 4,126,174 to Moriarty, et al. discloses a tensioned flexible sheet storage roller, a guide roller and side seal guides. These coverings are normally clear flexible materials that must be installed and removed as needed or can be rolled and stored in a storage area above the window. These materials can be tinted to provide a reduction in sunlight transmission, but tinting would also reduce vision at night. These storm window coverings offer good thermal insulation, but offer minimal protection from high wind velocity pressures and wind borne debris. Further, these coverings are usually made of flexible polyvinyl chloride and will functionally deteriorate with time and must be replaced. The coverings that are of rolling construction must have adequate clearance between the guide rails and the sheet to prevent jamming of the sheet in the guide rails during opening and closing.
U.S. Pat. No. 4,294,302 to Ricke, Sr. discloses a security shutter and awning device for covering windows and doors. The device includes slats made from aluminum or other extrudable material of sufficient strength to protect against storms and/or vandalism. The shutter of Ricke, Sr. may be slidably mounted and pivoted so as to act as an awning.
U.S. Pat. No. 4,601,320 to Taylor discloses a pressure differential compensating flexible curtain with side edge sections which are sealingly engaged with channels. The first upper end of the curtain is attached to a curtain winding mechanism which includes a spring barrel. Taylor discloses an elastomeric curtain having plastic supports with rubber covers banded thereto. Alternatively the plastic supports may be high molecular weight plastic strips. The purpose behind the design of the supports is to minimize the friction of these supports enabling operation of the door/curtain with a high differential pressure across it.
U.S. Pat. No. 4,723,588 to Ruppel discloses a roller shutter slat which interlocks with the adjacent roller sheet slat. U.S. Pat. No. 5,657,805 to Magro discloses a wind-resistant overhead closure with windlocks on the lateral edge portions of the intermediate and bottommost slats of the closure. First means to limit the lateral movement of the lateral edge of the intermediate potions and second means to limit the lateral movement of the endmost door portion are disclosed. Intermediate slats and endmost slats are provided. The ""805 patent indicates in col. 2, lines 12 et seq. that it conforms with the South Florida Building Code, 1994 Edition, previously referred to hereinabove. Further, the ""805 patent states that its teachings are applicable to both doors and windows.
Windlocks can be added at the end of slats which will improve the resistance of multileaf shutters or doors to wind velocity pressures by transmitting the stresses on the continuous hinge area to the ends of the slat, to the guide system and finally to the jambs or building structure. In order for the windlocks to engage the guide track the slat must deflect a considerable amount. Normally clearance is allowed between the guide track and the windlock to keep the door from jamming during operation and the more clearance allowed the more deflection of the slats before the windlocks contact the guide track. Typically, these windlocks are larger in cross section than the slat profile and when the shutter or door deflects from high wind velocity pressures, the windlocks are designed to engage the same space in which the slats are guided. When storing a rolling multileaf shutter or door equipped with windlocks, additional room is needed because the depth of the windlock is larger than the slat profile, the diameter of the storage area increases dramatically. In these designs, clearance between the windlock and the track must be allowed to prevent the windlocks from jamming and care must be taken when operating shutters or doors in a wind because the windlocks will sometimes jam as the product deflects.
U.S. Pat. No. 5,445,902 to Lichy discloses a damage minimizing closure door somewhat similar to U.S. Pat. No. 4,478,268 to Palmer. The Lichy ""209 patent discloses a flexible curtain and a guide for receiving and guiding the side edges of the flexible door during vertical movement. A counterbalancing power spring is associated with the door to assist in raising and lowering the curtain. Side edges of the curtain separate from the guide assembly upon being impacted by an externally applied force such as a vehicle.
U.S. Pat. No. 5,482,104 to Lichy discloses in FIG. 17 thereof, a flexible curtain and double windlocks which breakaway from the channel upon the application of excessive force to the curtain. See, col. 7, lines 33 et seq. U.S. Pat. No. 5,131,450 to Lichy discloses in FIG. 6 thereof a double edged guide and a curtain edge with two loose portions sewn to the transverse curtain. See, col. 6, lines 21, et seq. U.S. Pat. No. 5,232,408 to Brown discloses a flexible tape drive system wherein the tape is relatively rigid and it is driven by a toothed cog to provide both push and pull capabilities. U.S. Pat. No. 5,048,739 to Unoma, et al. illustrates a conical toothed drive paper feeder.
Conventional storm curtains without windlocks to engage into guides will pull out of the guides. This is especially true of wider curtains where they might be partially lowered for shading purposes without attaching storm bars required for storm protection. If, while lowering, or subsequent to lowering, wind forces exist that are significant but in no way threatening, the storm curtains typically escape from the guides due to excessive deflection of the slats. When this occurs, the slats become damaged as well as the facade surrounding the guide area becomes damaged as the ends of the slats typically rake the surrounding area in the process of escaping. The majority of applications for conventional storm curtains do not use windlocks. Rather than using windlocks, the problem of excessive curtain deflection which causes the curtain to escape from the guides is addressed with the use of storm bars. Storm bars, however, have disadvantages.
Storm bars create a passive system i.e. in the event of a severe storm they need to be taken out of storage and attached in predetermined locations across the span of the curtain. A wide curtain may require as many as three sets of storm bars. Sets consist of two bars in close proximity to each other in such a way as the curtain passes between the two bars. This addresses deflection that occurs in both positive and negative directions. Positive deflection is in the direction of the building and negative deflection is away from the building. At each storm bar location, brackets must first be attached to the floor, soffit and sills. Depending on the surrounding construction materials, secure locations are often difficult to find. After the brackets are attached to the building, the next step is to attach the storm bars to the brackets. Care must be taken to number and code the brackets to the matching storm bar, otherwise the pre-drilled holes for the bolts will not line up with the holes in the storm bars. Also, care must be taken to match and code the storm bars to their various locations since even a slight variation in the bar length causes the holes in the storm bar to misalign with the pre-drilled holes in the building facade. Also, these pre-drilled holes in the facade are permanent and cause problems aesthetically when the storm bar brackets are removed. Given the problems associated with escaping storm curtains, the building owner faces a dilemma when moderate storms are predicted such as severe summertime thunder storms. The daunting task of attaching the storm bars cannot be justified for every storm. Because the risk of damaging the storm curtains without attaching the storm bars is so great, the curtains are not utilized in moderate storms. Therefore, the building owner has a protection system that is either xe2x80x9con or off,xe2x80x9d xe2x80x9conxe2x80x9d meaning storm bars and curtains and xe2x80x9coffxe2x80x9d meaning nothing at all.
Conventional storm curtains do not have windlocks to prevent the slats from escaping the guides because windlocks have a larger cross section than that of the slat and using windlocks increases storage coil diameter which is a major limiting factor. With windlocks of the related art, storm curtains have a tendency to bind in the guides/tracks when being lowered because of the deflection of the curtain in moderate wind conditions. Enough friction is created, windlock to the inside edge of the guide, to cause the curtain to become obstructed and create unwanted accumulation of slats in the coil storage area. Additionally, adding windlocks to the ends of slats is very labor intensive and creates many more parts to drill and attach.
The instant invention addresses these three issues. The first issue with conventional storm curtains, that being an increase in coil storage requirement, is addressed by utilizing an interrupt formed on the ends of the tension rods of the instant invention which does not increase the requirement for coil storage when the curtain is stored.
The second issue regarding binding of the curtain is addressed by the instant invention since the tracks are mounted at a divergent angle with respect to each other and contact with the interrupts in the rod and the xe2x80x9cJ-shapedxe2x80x9d channel does not occur until the guide is in a fully closed position minimizing friction. Further, in the instant invention, unwanted accumulation in the coil storage area does not occur and the drive system is able to generate downward closing forces that overcome minimal friction that may occur between the interrupt and the xe2x80x9cJ-shapedxe2x80x9d channel.
Finally, regarding the issue of windlocks being labor intensive, the interrupts formed near the ends of the rods in the instant invention are made with a single stroke of a press after the rods are inserted into the curtain and, as such, do not make the windlock system labor intensive.
The instant invention uses light weight materials that have stiffness in the direction of the opening and closing but will bend around a radius as small as 0.5 inches. This strengthens the curtain by uniformly spreading the stresses developed by wind velocity pressure or impact over the width of the curtain and transferring the stresses to the track and to the structure of the building.
The invention adds tension to the elements of the curtain in the direction along its width or perpendicular to the force that is created by wind velocity pressure or impact from debris. The tension is directly proportional to the wind velocity pressure or impact from debris. Angled guide tracks may be used that tension the curtain when the curtain is closed without jamming the curtain in the guide tracks. Metallic, non-metallic materials (or a combination of both) may be used and they may be and can be opaque or transparent.
The windlock feature of the instant invention is incorporated into the curtain without affecting the thickness of the curtain and therefore does not affect the size of the storage area. The mass of the curtain is low allowing precise control of raising and lowering the curtain with a small power source and can be battery powered. Materials such as aramid fibers may be used thus making the curtain bullet proof.
An apparatus and method for windlocking a curtain covering and protecting an opening in a building is disclosed and claimed. The windlocking curtain resides to the exterior of the window, door or other opening and protects it from the intrusion of air, water or debris. In its upper position the windlocking curtain permits normal use of the opening and in its lower position it secures the opening. A flexible corrugated curtain has tension rods therethrough and the tension rods run in tracks on each side of the curtain and necessarily on each side of the opening. Interengagement of the tension rods with the tracks is accomplished by deformations in the rods that are referred to as interrupts. In one embodiment the rods are successively longer from top to bottom of the curtain and their interrupts matingly wedge with angled tracks to secure the curtain. In another embodiment the interrupts matingly engage parallel tracks upon the application of force due to wind, fluid (usually water or sea water) or debris. In another embodiment tension rods and interrupts are not used or necessary and a flap on the edges of a three-ply flexible curtain engage the interior of the side tracks absorbing shocking and sealing the opening. A method for securing the opening utilizing the apparatus is also claimed which provides top, bottom and side securement.
The flexible curtain comprises part of a curtain system for covering an opening in a building. A frame is affixed to an opening in a building. A flexible, corrugated curtain has a plurality of rods extending through some of the corrugations of the curtain. Preferably the rods, sometimes referred to as the tension rods, are rectangular in cross-section so as to provide maximum strength of the rod. Other cross-sectional sizes may be used. Angled tracks are provided in one embodiment which mate and wedge with angled interrupts when the curtain is in its second, closed position. When the curtain is open, it is in its first position and resides primarily on a counterbalanced windup reel. Each successive tension rod is longer than the prior rod so as to engagingly wedge with the angled tracks. The tracks are angled away from each other when the top point of the tracks are taken as the reference points. In other words, the tracks are at a divergent angle and get farther apart at the bottom.
The tension rods include a deformed portion sometimes referred to as an interrupt. The purpose of the interrupt is to matingly engage the tracks. In the embodiment which employs tracks which diverge from the top to bottom, the preferred divergent angle is one-half of one degree. Specifically, each track is diverging with respect to an imaginary vertical line at an angle of one-half degree making the total divergence for two tracks equal to one degree. One-half to one degree divergence from vertical per track (one to two degree divergence for both tracks) has been found to work well. Larger divergence angles require necessarily deeper tracks and larger interrupts particularly if a long building opening is to be protected. Those skilled in the art will readily realize from reading this disclosure that other angles may be used depending on the size of the opening to be covered.
Corrugated flexible curtain is used in one embodiment as stated above and slits therein may be employed in the face of the curtain to improve the flexibility for storing on the counterbalanced wind-up reel. In regard to storage of the curtain and tensioning rods, the deformations of the tensioning rods (interrupts) do not increase the space required for storage because the thickness of the tension rod is not increased in the direction of the radii of the wind-up reel.
Operation of the flexible curtain is enhanced by using divergently separating track as the occurrence of jamming is minimized. All of the tension rods are designed to engage the angled tracks at approximately the same time creating a wedge effect since the interrupts are deformed at a mating angle which matches the angle of the track.
Another embodiment of the invention employs parallel tracks and the tension rods do not engage the tracks except during times when they are loaded. In this embodiment the tension rods are all the same length and when the curtain is closed in its second position the lips of the interrupt do not engage the track. When the wind velocity becomes sufficiently high, the curtain deflects and pulls the mating surfaces of the interrupts into engagement with the track.
Another embodiment of the invention employs tension rods having a ninety degree radius at the ends thereof and eliminates the need for interrupts. It is the ninety degree radius which engages the angled/parallel tracks.
Rectangular apertures exist in the flexible corrugated curtain for engagement with teeth of a driving gear or gears. The gears, under resistance of a counterbalance spring affixed to the wind-up rod, drive the curtain from a first, open position to a second, closed position. All embodiments disclose rectangular curtains. Standard window dimensions are 30 to 36 inches wide and 30, 38 or 54 inches long. However, longer and wider openings can be secured with the embodiments of the invention disclosed herein. Corrugated curtains can be driven with a single gear or with dual gears. Openings in buildings of all sizes may be protected using the principles of the invention.
Alternatively, a driven adapter rack and/or an adapter rack and a gear may be simultaneously used to drive the tension rods.
Another embodiment employs a flexible curtain comprising three-plies laminated together. The plies may be laminated together under the influence of heat and pressure. Additionally adhesive may be used to secure the plies together. Two outer plies or sheets are polymeric and the inner ply is woven. A living seal is formed on the edges of the curtain by folding the edges of the curtain back on the curtain itself. The folded portion is secured by stitching with thread, or by adhesive, or by heat fusing, or by ultrasonic welding. Only a portion of the folded flap is secured. Preferably two-thirds (⅔) of the folded flap is secured to itself and one-third (⅓) remains free. When the three-ply curtain is tensioned under the influence of wind or debris loading, for instance, the folded portion engages the interior of the track which houses the folded portion preventing its escape therefrom. Further, the folded flap provides a total seal which is sometimes referred to herein as a living seal. The free portion of the flap provides a shock absorber which cushions the frame against time variant forces which may be applied due to fluctuating wind and/or debris. The three ply curtain may also be used with angled track by slitting the outer face of the three ply curtain. The slitting provides a loose flap which engages the track.
Cylindrical apertures reside in the folded portion of said three-ply curtain and the drive cog interengages the apertures for raising and lowering the curtain against the force of the counterbalance spring. Preferably, there is a folded portion on each side of the curtain residing in its respective track and being driven by its respective drive cog. Conically shaped cogs fit the apertures well and, additionally, the apertures may be fitted with eyelets. A bowed bottom bar is secured within a folded portion of the curtain and guides the curtain into a slot. In other words, the curtain is slightly longer at its edges than in the middle such that as the curtain is coming down for securement in the second, closed position the sides enter the retaining slot first. If the curtain is being closed during a strong wind event, the middle of the curtain may be deflected slightly inwardly but the side portions are not because they are within the tracks which are directly aligned with (above) the retaining slot. This enables the bottom bar to begin seating in the retaining slot at the side edges and guide the bottom bar into place. Additionally, the weight of the bar assists in positioning it in place in the retaining slot. Additionally, a living seal formed by a flap extending from the stitched or heat sealed bottom bar may be employed in a modified retaining slot sometimes referred to herein as a storage slot.
Another embodiment of the bottom bar interengages a sill or bottom member having a seal therein. The bottom bar may be affixed to the bottom of the curtain by any one of several known fastening devices such as rivets, bolts and threads, and the like. The curtain system covers a window, door or other opening a building. The curtain system may reside to the exterior of the window, door or other opening or it may reside to the interior of the window, door or other opening.
Accordingly, it is an object of the present invention to provide a low cost and light weight flexible curtain which develops transverse (side to side when viewed from the front) tension each time the curtain closes.
It is a further object of the present invention to provide a curtain system which uses a light weight counterbalance because of the lightweight construction of the curtain.
It is a further object to provide a curtain having windload and impact resistance which is always active when the curtain is closed and requires no other action by the user in the event of a high velocity wind occurrence.
It is a further object to provide a curtain which will not jam and cause damage to the curtain during operation even if operated during high wind occurrences.
It is further object to provide a storm curtain which stores within standard wall thickness found in the United States. It can be incorporated into the window frame in such a way that the storm curtain does not require additional framework or cover for protuberances created by the larger storage coil diameters typical of conventional storm curtains.
It is a further object of the present invention to provide a curtain system which resides to the exterior or the interior of the window, door or other opening in a building.
It is a further object to provide a low maintenance storm curtain. Conventional storm curtains require periodic high pressure washing especially along coastal areas where they are exposed to salt spray and blowing sand. Conventional storm curtains are designed so that the longitudinal edges of the slats telescope into each other approximately three-eighths inch (xe2x85x9cxe2x80x3) to one-half inch (xc2xdxe2x80x3) as shown in U.S. Pat. No. 4,173,247 to Prana and U.S. Pat. No. 5,322,108 to Hoffman. The telescoping portion of the slat is exposed when the storm curtain is partially closed, typically for sun control, and because of the weight of the slat suspended below, the slats will be extended from each other. When salt spray and sand accumulate on this portion of the surface of the slat, abrasion and friction will interfere with slat to slat telescoping. If the slats are not cleaned and pressure washed periodically, the lower slats usually start to malfunction first since they have the least gravitational force to cause separation. If this separation or telescoping does not occur and the slats enter the coil storage area they will be put into a severe bind and as a consequence, become damaged. Telescoping slats develop more beam strength when the longitudinal edges of the slats are telescoped into each other when fully closed. However, the maximum allowable radius requirement for the curtain to coil within the allocated storage area cannot be met unless the slat edges are fully extended from each other as they begin to articulate into the coil storage position. In the instant invention, the outside surface consists of a smooth polymeric material with no requirement to telescope. As such, there is no opportunity for salt spray and sand to accumulate in in regular surfaces. It is a further object of this invention to provide a smaller storage area.
Another advantage of the instant invention, unlike conventional storm curtains, is that the instant invention becomes taut from top to bottom when in a closed position. For this reason there is no chatter, banging or rattling that exists with conventional storm curtains in buffeting winds. Further, when the embodiment of the living seal is employed, the loose or free portion of the folded flap or strip absorbs shock and therefore does not transmit it to the surrounding frame. This will make a quieter system with low or no maintenance.
Still another advantage of the instant invention is that the storm curtain is directly linked to drive gears and a drive shaft which are engaged into perforations pierced into the curtain and essentially (but not actually) place the gear teeth in contact with the metal tension rods lodged in the corrugated curtain which, when activated, cause the curtain to be raised and lowered. The tension rods are completely sealed with respect to contamination by the corrugated material. In the embodiment of the three ply curtain, it completely seals against the intrusion of wind borne salt and debris.
Another advantage of the instant invention is that the storm curtain can be pre-installed into the window frame at the factory as a single unit. The sub-contractor normally involved in the installation of storm curtains is no longer required. Another problem frequently encountered and avoided with the instant invention is related to the typically varied conditions prevalent on job sites. With a wide range of window configurations depending on the manufacturer and varied contractor preferred framing methods and sill details, these variations often complicate the installation of storm curtains. This can greatly increase the cost of installation where additional re-framing may be required or where other modifications need to be made so the storm curtain can be installed correctly. In the instant invention, the storm curtain is pre-installed into the window framework and these problems do not exist.
Another advantage of the instant invention is that since the interrupts pressed (deformed) into the metal rods embedded in the curtain are engaged into the xe2x80x9cJ-shapedxe2x80x9d track, the curtain cannot escape or xe2x80x9cblow outxe2x80x9d.
Another advantage of the instant invention is that the track comprises two pieces. This enables easy manufacture of the pieces while providing a strong track when the pieces are assembled together. When the wind, debris and water tensions the curtain either in a positive direction or a negative direction, a strong and stable track affixed to the building adjacent an opening is required. Positive deflection is in the direction of the building and negative deflection is away from the building. The two-piece track construction is interlocked together and may be screwed, welded, tack-welded, ultrasonically welded if made from plastic, bound by adhesive, and/or riveted. In this way the two piece construction provides a strong and stable track which is necessary to absorb the reaction forces of the wind, debris and water which impact the curtain.
Instead of the two-piece frame being mechanically fastened together through the use of fasteners, it may be secured together through a sliding interlocking fit. The interlocking fit has the advantage of continuous engagement over the length of the track. Manufacture of the two pieces is thus greatly facilitated since it is much easier to manufacture them separately and the interlocking fit provides great strength. Although the preferred material of the track is metal such as aluminum, it may be made from plastic.
It is a further object and advantage of the instant invention to provide a track which has gentle contours which engage the curtain as it is tensioned such that the curtain is not cut or torn. During violent wind conditions the kinetic energy of the wind will cause the curtain to suddenly engage the track. The track includes contours which engage the curtain so as to minimize cutting of the curtain under loaded conditions. Additionally, the contours of the track seal against a coating on the flexible curtain. The flexible curtain is a polymeric material and it may be reinforced with polyester. Further, the flexible curtain may be coated with a silicone or polyvinyl chloride or the like. The coated surface is a smooth surface which engages the contours of the track under loaded conditions to provide a seal.
A better understanding of the objects and advantages of the invention will be had when reference is made to the Brief Description of the Drawings, Description of the Invention and Claims which follow hereinbelow.